Intravenous needles used for injecting or withdrawing blood, volume increasing fluids, feeding fluids, medications, blood transfusions and the like are normally inserted directly into the blood vessel by hand. Under certain pathological or traumatic conditions, particularly when blood pressure is unusually low, blood vessels lying close to the skin, such as in the arm or leg are substantially collapsed, making it difficult, if not impossible, to find the lumen upon insertion and manipulation of the needle or cannula through a skin puncture. This condition is especially critical when a patient is in shock due to excessive bleeding or internal hemorrhaging. If a licensed physician is in attendance, the emergency procedure known as a venous "cut-down" can be resorted to, exposing the vein to permit surgical cutting and direct insertion of a catheter. However, in many emergency situations in which a patient is in shock because of extensive hemorrhaging, an emergency medical technician is first to arrive at the scene to offer medical treatment. This is particularly true in the case of automobile and industrial machine accidents resulting in severe injuries to the patient. Since emergency medical technicians are normally not authorized to perform a surgical "cut-down" procedure, they must, under most such emergency conditions, use their best skills to manually insert an intravenous needle through the skin into the lumen of a vein, even though the vein is in a collapsed or partially collapsed condition due to low blood pressure. This is an extremely difficult task.
The foregoing difficulties have been recognized by a number of prior art practitioners. For example, U.S. Pat. No. 4,299,219 issued to Norris, Jr. on Nov. 10, 1981 discloses an intravenous needle insertion device having a transparent vacuum cylinder with an open end adapted for placement in sealing engagement over the skin of a patient at a zone where venipuncture is to be performed. A vacuum drawing syringe communicates with the cylinder for establishing a vacuum which serves to draw the skin and underlying vein partially into the vacuum chamber. According to the teachings of Norris, Jr., the vein will become engorged with blood to facilitate needle insertion. An intravenous needle holding and manipulating assembly is substantially coaxially arranged within the vacuum cylinder and hermetically sealed with respect thereto. The device further includes release mechanism at the open end of the vacuum cylinder for temporarily supporting an intravenous needle as well as manual grasping means at the other end to permit manipulation of the needle for insertion in the distended vein while under vacuum.
The device disclosed by Norris, Jr. et al. would, however, pose several practical difficulties in use. The first is that the medical technician would have to make an initial decision as to which vein will be entered and very precisely where the puncture is to be made, since the needle is substantially coaxially supported in the transparent vacuum cylinder. Furthermore, even if the needle of Norris, Jr. et al. were capable of slight laterial movement, the transparent cylinder would prevent the medical technician from selecting the best possible site for venipuncture after the pressure inside the chamber has been reduced, since the selection of a suitable site for venipuncture normally depends more upon palpation than visualization. In addition, since the vein selected remains within the cylinder during insertion, the medical technician is unable to manually stretch the skin (this is normally done to minimize pain), to modify the angle of attack of the needle both vertically and horizontally, to stabilize the vein with the fingers or to feel the needle actually entering the vein. Finally, the unbalanced atmospheric force resulting with the device of Norris Jr. et al. creates pressure along the edge of the cylindrical surface at the point where the seal with the patient's body is achieved. This localized force tends to clamp the veins shut if they are near the surface. To offset this clamping action created by the vacuum, it would be necessary to provide a balancing force to pull the device away from the skin to eliminate or minimize restriction of the vein. Providing such a force makes it even more difficult to manipulate entrance of the needle into the lumen of the vein.
Accordingly, it is an object of the present invention to provide method and apparatus for safely and reliably entering the blood vessel of a patient with a needle or other suitable cannula, even if the patient is suffering from hypovolemic or other forms of shock.
It is another object of the present invention to provide a multiplicity of unobstructed sites where insertion of a needle into a blood vessel is readily permitted, and the particular site to be employed can be chosen at the discretion of either the patient or the medical practitioner after the blood vessels are distended.
It is still another object of the present invention to provide method and apparatus for distending the blood vessel prior to venipuncture so that actual puncturing of the vessel by the needle is more easily facilitated.
It is still another object of the present invention to provide method and apparatus for accomplishing the foregoing objectives which are simple to apply by non-technically trained personnel, which are incapable of causing injury to the patient and which are sufficiently inexpensive that they can, if desired, be readily discarded after a single use.